The two-digit number after the slash mark in a tire size is the aspect ratio. For example, in a tire size P225/50R17 tire, the 50 means that the height is equal to 50% of the tires width. The bigger the aspect ratio, the bigger the tire’s sidewall will be. Usually the lower the two-digit number, the wider the tire.
R= Radial Tyre. P=passenger
The three digits (225) following the service type, tell us the cross-section width of the tire in millimerters.
In the example, the 50 width tire will bethe wider tire, whiler 55 will be slightly taller.
A lower aspect ratio means a lower-profile tire with a shorter sidewall, while a tire with a higher aspect ratio will have a taller sidewall and look more like a donut.
From above, the 17 means that the tire should be matched to a 17 inch diameter wheel.
